New millimeter wave interferometric, multifunctional sensors have been studied for
industrial sensing applications: displacement measurement, liquid-level gauging and
velocimetry. Two types of configuration were investigated to implement the sensor:
homodyne and double-channel homodyne. Both sensors were integrated on planar
structure using MMIC (Microwave Monolithic Integrated Circuit) and MIC (Microwave
Integrated Circuit) technology for light, compact, and low-cost design. The displacement
measurement results employing homodyne configuration show that sub-millimeter
resolution in the order of 0.05 mm is feasible without correcting the non-linear phase
response of the quadrature mixer.
The double-channel homodyne configuration is proposed to suppress the nonlinearity
of the quadrature mixer and to estimate the effect of frequency stability of a
microwave signal source without the help of additional test equipment, at the loss of a
slight increase of circuit complexity. The digital quadrature mixer is constituted by a
quadrature-sampling signal processing technique and takes an important role in the
elimination of conventional quadrature mixer's nonlinear phase response. Also, in the
same displacement measurement, the radar sensor with the double-channel homodyne
configuration provided a better resolution of 0.01mm, the best-reported resolution to
date in terms of wavelength in the millimeter wave range, than the sensor employing
simple homodyne configuration.
Short-term stability of a microwave signal source, which is an important issue in
phase sensitive measurement, is also considered through phase noise spectrum obtained
by FFT spectral estimator at Intermediate Frequency (IF).
The developed sensors demonstrate that displacement sensing with micron
resolution and accuracy and high-resolution low-velocity measurement are feasible using
millimeter-wave interferometer, which is attractive not only for displacement and
velocity measurement, but also for other industrial sensing applications requiring very
fine resolution and accuracy.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3134 |
| Date | 12 April 2006 |
| Creators | Kim, Seoktae |
| Contributors | Nguyen, Cam |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1720166 bytes, electronic, application/pdf, born digital |
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